Corona discharge device for destruction of airborne microbes and chemical toxins

ABSTRACT

A miniature air purifier produces a corona discharge surrounding a needle-like emitter point connected to a negative DC power supply. The power supply operates from a nine volt battery and contains a step-up voltage inverter having a single transformer outputting high voltage spikes with a voltage multiplier operating on the output of the inverter. The production of high voltage spikes of about 200 Hz rather than a sinusoidally varying voltage significantly reduces current consumption. The needle-like emitter point is located about 1/4-inch from an 80% open mesh metallic grid held at ground potential. Corona discharge at the emitter point ionizes the air and creates ozone, and nitric oxide both of which combine with direct electron impact decomposition to detoxify and destroy a wide variety of airborne pollutants including pathogens, chemicals and allergens. The grid attracts negatively ionized air molecules thereby creating a flow of purified air out of the device and also provides a surface for electroprecipitation of ionized particulates. An alternative embodiment of the present invention can combine a series of emitter points in a sterilizer to provide a microbial neutralization in the food service industry.

RELATED APPLICATIONS

This application is a continuation of Ser. No. 08/931,101, filed on Sep.15, 1997, now U.S. Pat. No. 5,814,135, which is a continuation-in-partapplication of Ser. No. 08/696,624, filed on Aug. 14, 1996, now, U.S.Pat. No. 5,667,564.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention involves the field of electronic air purificationand, more specifically, a miniature device that generates a coronadischarge to detoxify, and circulate air around an individual's face.

2. Description of Related Art

The present invention represents an improvement to the instantinventor's earlier invention entitled "Miniature Air Purifier" filedFeb. 6, 1995, and now issued as U.S. Pat. No. 5,484,472. That patentdescribes a miniature wearable unit that directs a current of ionizedair towards the face of a wearer to help prevent the inhalation ofvarious toxins and irritants that are increasingly present in ourenvironment. For a summary of various earlier approaches to the problemsof ameliorating contaminated air, the reader is directed to that earlierpatent which is incorporated herein by reference.

The problem of air pollution can hardly be overstated. It has beenvariously estimated that as many as 80 million Americans suffer from airpollution that results in large numbers of premature deaths each year.It has been reported that children growing up in especially pollutedareas like the Los Angeles basin end up with permanently damaged lungs.The problem may be even more acute in large cities of the Third Worldwhere environmental controls are more lax than in the United States.While increased governmental regulation poses one solution to thedanger, what are affected individuals to do in the meantime? One caninstall various home air purifying devices, but this does no good whenone has to travel about away from the home.

The present inventor has previously offered a portable air purifier as asolution. This earlier miniature air purifier was characterized by itssmall size allowing it to be worn clipped to one's clothing or on a cordabout one's neck. However, the need to incorporate fairly complexelectronic circuit board including two inductor components resulted inthe unit having a dimension of at least 21/2×4×1 inches and weighing atleast 7 oz. The circuit of that device required a significant currentflow from the battery, which considerably limited battery life.Typically, the unit would operate for about 10-15 hours using a freshalkaline battery.

The primary routes of air purification in the earlier air purifier werechemical destruction of pollutants by ozone and the corona discharge andelectrostatic precipitation of particulates as a result of charging bynegative ions. The primary source of air flow was a mass air flow due toacceleration of negatively ionized air molecules towards a groundedmetallic grid.

Because ozone can be irritating to the respiratory system, it isdesirable to provide a more effective corona discharge for destroying awider range of chemical pollutants while, at the same time, limiting theamount of ozone emitted. There remains a considerable need for aminiature air purifier that is very efficient at producing a coronadischarge for better removal of pollutants and longer battery life withminimal emission of ozone.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a miniature airpurifier that can operate for about 50 to 60 hours on a typicalnine-volt alkaline battery;

It is a further object of the present invention to provide a miniatureair purifier with a simplified circuit using only a single inductivecomponent to reduce the size and weight as well as the cost of thedevice and to reduce generation of radio frequency interference;

It is a still further object of the present invention to optimize coronadischarge purification to maximize killing of pathogens, oxidize thetoxins produced by the pathogens, detoxification of chemical pollutants,and neutralization of allergens while minimizing release of ozone; and

It is an additional object of the present invention to provide an smallwearable air purifier that includes an alternative embodiment that alsoprecleans air by means of pollutant and pathogen filters prior to thecorona discharge.

These and additional objects are met by a miniature air purifier thatproduces a corona discharge around an emitter point connected to a novel8,000-volt DC power supply. The power supply operates from a singlenine-volt battery and contains a step-up voltage inverter having asingle transformer and a voltage multiplier operating on the output ofthe inverter. The needle-like emitter point is located about 1/4-inchfrom an 80% open mesh metallic grid held at ground potential. A coronadischarge surrounds the emitter point and produces ionized air as wellas destroying pathogens and pollutants with ozone and direct electronimpact decomposition. The grid attracts ionized air molecules, therebycreating a mass flow of purified air out of the device, and alsoprovides a surface for electroprecipitation of particulates. Analternative embodiment uses a miniature brushless DC fan to draw roomair through a pathogen and pollutant removing filter. The filtered airis exposed to the corona discharge for additional purification and thenaccelerated out of the device by the emitter point and grid.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention, which are believed tobe novel, are set forth with particularity in the appended claims. Thepresent invention, both as to its organization and manner of operation,together with further objects and advantages, may best be understood byreference to the following description, taken in connection with theaccompanying drawings.

FIG. 1 shows a perspective drawing of the present invention;

FIG. 2 shows an alternate embodiment of the device of FIG. 1 with a fan;

FIG. 3 shows a diagrammatic representation of the operation of thedevice of FIG. 2;

FIG. 4 shows a diagram of an electronic circuit of the presentinvention;

FIG. 5 shows a cut-away view of the embodiment of FIG. 2 showing theflow of air;

FIG. 6 is a graphic diagram of the voltage spikes produced by thecircuit of FIG. 4;

FIG. 7 is a graph showing the destruction of air borne bacteria by thepresent invention;

FIG. 8 is a prospective view of a modification of the air purifier foruse with food products;

FIG. 9 is a partial prospective view of the hood of FIG. 8; and

FIG. 10 is a prospective view of an alternative hand held wand-type ofsterilizer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is provided to enable any person skilled inthe art to make and use the invention and sets forth the best modescontemplated by the inventor of carrying out his invention. Variousmodifications, however, will remain readily apparent to those skilled inthe art, since the generic principles of the present invention have beendefined herein specifically to provide a miniature air purifier withimproved efficiency and reduced size.

FIG. 1 shows a perspective drawing of one embodiment of an air purifier10 of the present invention cut away to show interior construction. Itis shown next to an outline 25 of a conventional pager to indicate theunit size. This represents a considerably smaller package than thatprovided by this inventor's earlier invention or of any other portableair purifier of which this inventor is aware. The unit is generallyrectangular with an ON/OFF switch 18 and a connector 19 for an ACbattery adapter. The miniature electronics of the unit 10 are powered bya conventional nine-volt alkaline battery when the adapter is notconnected.

The upper end of the unit 10 bears an opening 23 covered by a metallicgrid 24 through which the purified air exits. A metallic needle-likeemitter point 26 is mounted on a high voltage circuit module 32 and islocated about 1/4-inch below the grid 24. In use air near the emitterpoint 26 becomes ionized by a corona discharge developed by a highvoltage (about 8 kV) supplied by the high voltage circuit module 32. Itis important to note that while prior art devices, including the presentinventor's earlier air purifier, generally use higher voltages, i.e., 15kV or higher, it was unexpectedly discovered during the development ofthe present invention that lower voltages, i.e., below about 10 kV,yield a vigorous corona discharge and mass air flow while producing adramatically lower level of ozone. Further, those of ordinary skill inthe art will realize that either a positive or negative high voltage canbe used to produce a corona discharge. The electronic circuits describedbelow can be configured to produce either positive or negative highvoltage. The unit operates adequately with either positive or negativecorona discharge.

The metallic grid 24 is preferably nickel plated with about 80% openarea and is held at ground potential relative to the emitter point 26 sothat ions produced in the corona discharge are accelerated towards thegrid 24. This results in a mass flow of air (i.e., the ionized moleculespull along a large number of nonionized molecules by means of cohesiveforces) which propels the purified air out through openings (largearrows) in the grid 24. As purified air exits and is propelled towardsthe face of the wearer, room air (dotted arrows) is drawn in at thesides of the opening 23. At the same time the corona discharge providesionizing energy and ozone to chemically destroy pollutants or pathogensthrough electron (plasma) impact decomposition. By adjusting the processto produce less ozone one is better able to balance ozone to averagepollutant load. The majority of ozone is consumed reacting withpollutants before the air exits the purifier 10. Particulate matterproduced during this destruction process is usually charged so that itis accelerated towards and precipitates on the metallic grid 24.

As a further improvement in reducing the emission of ozone, it ispossible to coat the metallic grid 24 with a layer of ManganeseChloride, M_(N) CL₂, or Manganese Dioxide, M_(N) O₂, to act as acatalyst in converting the ozone into oxygen. It is believed that such acoating can further reduce the ozone level by 20% to 30%.

FIG. 2 shows a perspective drawing of an alternate embodiment of the airpurifier 10'. This unit is the same size as the unit of FIG. 1 and usesthe same improved electronics that will be explained below. The majordifference between this unit 10' and the unit 10 of FIG. 1 is theability of this alternate embodiment to utilize modern filteringmaterials to remove pollutants and pathogens prior to the coronadischarge. The unit is of the same dimensions as the unit of FIG. 2 butalso has an air intake 12 on one of its larger side surfaces. The airintake 12 is covered by a removable filter 14 held in place by a strip16 of VELCRO® hook and loop fastener or some similar fastening system.Like the device of FIG. 1, unit 10' also has an ON/OFF switch 18 and aconnector 19 for a battery adapter and is powered by a conventionalnine-volt alkaline battery cell 22.

While the mass flow of air provided by the corona discharge is adequateto propel a stream of purified air out of the device, as explained inrelation to FIG. 1, the inventor has found that the discharge mediatedflow is generally not sufficient to pull air through a particulate orpollutant removing filter. Therefore, a miniature fan 15 has beenprovided. This fan is preferably one of the DC brushless types andoperates at a low speed and uses very little power because its only taskis to move air through the filter 14. Alternatively, a piezoelectric fancan be substituted for the brushless DC fan. FIG. 3 shows a simplediagram of the filter 14, fan 15, and emitter point 26 arrangement. Airis drawn through the filter 14 by the fan 15. The filtered air is thenionized by the emitter point 26 and is accelerated towards the grid 26.In nonportable prior art devices, fans have been used to move airthrough filters and propel it out of the device. Such powerful fansconsume too much electricity for use in a portable device. The presentinventor has found a low power alternative which uses the fan solely topull air through the filter. The filtered air is then accelerated out ofthe device by the corona discharge.

The filter 14 can contain any of a number of filter materials. A HEPA(High Efficiency Particulate Air) filter can be used to remove bothparticulates and pathogens. Other popular filtering material such asglass wool or polyvinyl acetal sponge can be advantageously used toremove particulates and pathogens. Alternatively, a filter impregnatedwith a germicidal agent such as iodine can be used for pathogeninactivation. An activated carbon filter such as those of activatedcoconut charcoal can be included to remove chemical pollutants. Zeolitefiltering materials can also be used to efficiently remove pollutants.All that is necessary is to ensure that the filter material issufficiently porous that the fan 15 is able to pull sufficient airthrough the filter 15.

While the optional filter 14 directly absorbs particulates and toxicmaterials, the corona discharge actually destroys many pollutants nottrapped by the filter 15. A corona discharge is an unusually powerfuloxidizing source. Ozone produced by the discharge is chemically veryactive and oxidizes many pollutant chemicals and also inactivatespathogens and allergens. Besides ozone-mediated oxidation, there istremendous destruction of airborne chemicals by direct electron (plasma)impact decomposition within the corona discharge. Particulates passingthrough the discharge without being incinerated become charged so theyprecipitate out on grounded surfaces like the metallic grid 24. Organicchemical decomposed by the corona discharge often yield particles ofcarbon that also precipitate out on the grid 24. In actual operation thedischarge-facing surface of the grid 24 often becomes blackened andcoated with precipitated and oxidized material. An advantage of using afilter to remove some of the organic pollutants prior to the coronadischarge is that this prevents some of the precipitation on the grid 24thereby extending the period of time between grid cleaning.

During the development of the present device the inventor discoveredthat it is important to adjust the rate of air movement through thecorona discharge to obtain optimum destruction of pollutants. If the airmoves too rapidly, the pollutants do not spend sufficient time in thedischarge to ensure their destruction. The rate of air movement isaffected by the potential difference and the geometrical relationshipbetween the emitter point 26 and the grid 24. In the case of theembodiment with the fan 15, it is important to adjust the fan 15 and thefilter 14 so that that the air is not propelled too rapidly through thecorona discharge. With the present geometry and accelerating voltage theoptimum rate of air flow out of the grid is about 50 ft/min. At lowerflow rates the expelled air may not reach the user's face. At higherflow rates there is insufficient residence time in the corona dischargeto obtain optimal destruction of pollutants.

FIG. 4 shows a circuit diagram of the miniature electronics of the highvoltage circuit board 32. This circuit allows the unit 10 to be verysmall and light while also providing unusually long battery life. Whileit is desirable to have ozone present in the corona discharge zone so asto help inactivate chemicals and microbes, the potential forozone-caused irritation of mucous membranes makes it desirable tominimize the number of ozone molecules that actually reach the wearer ofthe unit. In experimenting with the prototypes of the present inventionin an effort to balance air flow and battery life, the present inventormade a surprising discovery concerning ozone generation. When currentflow into the high voltage generation system is limited and the highvoltage kept below about 10 kV, and preferably at no more than aboutnegative 8 kV, the level of emitted ozone drops dramatically withoutsignificantly impacting the mass air flow at the grid 24. This reductionof ozone production results in the electron impact effect of the coronadischarge predominating.

The unit contains a ferrite transformer T1 33 having a primary coil 35and a secondary coil 37 with a secondary/primary ratio of about 350/1.Current flow from the battery 22 (by way of S1 18) through the primarycoil 35 is controlled by an NPN transistor Q1 36, such as low voltageToshiba C 3279. The transistor 36 and transformer 33 form a step-upvoltage inverter which converts battery DC into AC at a higher voltage.As current begins to flow from the battery 22, through the primary coil35 and the transistor 36, it creates a rising magnetic field whichinduces a first rising voltage in the secondary coil 37. The windingratio results in the voltage being multiplied to range between 0 andabout 2,000 volts, while the primary voltage varies between 0 and 9volts. The gate 42 of the transistor 36 is attached to a center tap 44on the transformer 33. The rising voltage at the center tap 44eventually causes the transistor 36 to switch off the current flowthrough the primary coil 35, causing the magnetic field in the secondarycoil 37 to collapse.

The collapse of the magnetic field in the transformer T1 33 induces asecond voltage, of the opposite polarity to the first voltage, in thesecondary coil 37. The present inventor has found that using aresistance-capacitance network to shape the alternating current producedby the secondary coil 37 can dramatically alter the power consumption ofthe overall circuit. Resistors R1 (variable resistor to tune thecircuit), and R2 and capacitors C8 59, and C9 60, and C7 58 adjust thecircuit from one that would produce a sinusoidal voltage at Point A 34to one that produces a series of high voltage spikes. The voltage atPoint A 34 varies in polarity from about +2 kV to about -2 kV volts at afrequency of about 200 Hz. Because the output is voltage spikes, thecircuit draws only about 10 mA so that a nine-volt battery lasts forabout 60 hours. This frequency also appears to be important at gettingminimal ozone production while maximizing the other effects of thecorona discharge. FIG. 6 illustrates the high voltage spikes produced bythe circuit. The output consists of pulses or spikes wherein each spikeactually consists of a high voltage burst of about 50 microsecondduration every 5 msec. The tuning circuit mentioned above effectivelyperforms pulse position modulation with a higher frequency of pulsesconsuming more current and resulting in a higher air flow. R1 57 can beadjusted for each unit so that the optimal pulse frequency of about 200Hz can be set despite component variations from circuit board to circuitboard.

The high voltage spikes are fed into a high voltage multiplier 38. Theillustrated circuit is configured as a negative high voltage multiplier,but the circuit can also be configured as a positive high voltagemultiplier. The presently preferred design of the multiplier 38 acts asa voltage sextupler with multiple stages and a final pulsating outputvoltage of about -8 kV at Point B 46. The high voltage multiplier 38 hasstages containing high voltage (8 kV) diodes (D1-D6), and 6 kV, 100 pFceramic capacitors (C2-C6). A specially selected hot melt adhesive isused to comnformationally coat the high voltage circuits to preventinappropriate corona discharge and to encapsulate the system againstmoisture and other environmental factors. This treatment significantlyreduces energy requirements further adding to overall increase ofbattery life. This encapsulation results in much lower finished deviceweight (an important factor for wearability) than conventional epoxypotting techniques.

The high voltage produced by the multiplier 38 is connected to theemitter point 26 by relaxation oscillator 52 which consists of acapacitor C10 54 (0.015 mF) and a 100-volt neon lamp 56 connected inparallel. As electrons flow through the emitter point 26, the neon lamp56 flashes. This serves two purposes. First, it limits the current flow,and second, it serves as a visual cue that the unit is operatingproperly. Since the discharge is virtually without sound, the visual cueis especially helpful. The emitter point 26 is located about1/4-1/2-inch from the metallic grid 24, which completes the circuit tothe battery through a 10 megOhm resistor R3 58, which further limits thecurrent flow.

The disclosed grid-emitter geometry combined with the disclosed circuitproduces a discharge current flow of about 5 μA at an air flow rate of50 ft/min. At this current flow, according to Coulomb's law, there areabout 31,000,000,000 electrons per second available in the coronadischarge for ionizing and destroying pollutants through electronimpact.

Besides the physical sensation of moving cold air there is an additional"psychological" effect of well-being experienced by the user inhalingthe stream of purified air. Some of this effect is probablypsychological due to the "clean, outdoor" smell and taste of the mildlyozonated air. It is widely believed that the refreshing quality of theoutside atmosphere following the passing of a thunderstorm is due tothis ozone effect. An additional cause of the "psychological" effectcould well be an actual physiological response to trace levels of nitricoxide in the ionized air stream. Nitric oxide has recently been found tobe an important biological signaling molecule that is involved in neuralimpulse transmission and a host of other biological phenomena. It isalso known that application of nitric oxide to the lung reducespulmonary blood pressure and acts as a broncodilator. Nitric oxideproduction seems to require a negative plasma source while most of theother effects discussed above can be obtained through either negative orpositive corona discharge.

Nitric oxide my also contribute to the germicidal effect of the unit.Experiments performed by blowing bacteria laden air onto an exposedPetri plate surface have shown a dramatic drop in bacterial colonieswhen the contaminated air flow passes near to the grid 24 of a workingair purifier 10 before striking the Petri plate. Presumably, germicidalagents emitted by the device destroy air borne bacteria. Also, some ofthe contaminated air is probably drawn into the actual corona dischargeand directly disinfected. FIG. 7 graphically shows the results ofblowing bacteria laden air onto exposed Petri plates for differentperiods of time. A first bar (-) in each pair represents the number ofbacterial colonies (plates counted after incubation overnight at 37° C.)on plates after two or eight minutes of exposure to a steam of bacterialaden air. A second bar (+) in each pair represents the number ofcolonies when the bacterialaden air stream passed over an operating unitof the present invention before striking the Petri plate. Variouscontrol plates indicated that the bacteria were actually killed and notmerely deflected by the stream of disinfecting air released by thepresent invention. The disinfecting air reduced the number of bacterialcolonies by 90% (statistically significant at the 5% level). Thisdramatic effect was unexpected and opens the possibility of developing abacteria shield. Such a device could be used in place of a surgical maskand would protect both the patient and the surgeon. Significantly,negative corona discharge was at least 20% more effective at destroyingbacteria strongly suggesting that nitric oxide plays an important rolein disinfection.

The present invention can also be used as a sterilizer for foodpreparation. As shown in FIG. 8, a sterilizer 100 can be mountedadjacent a kitchen counter or a cutting board 108 to aerosolize thesurface and thereby reduce bacteria. The corona discharge provides anoxidizing environment that is believed to destroy bacterial spores andtoxic organic material. Experiments on E.coli MV1190 and E.coli MC4100indicated a 90% microbial neutralization. It is believed that equivalentresults will be obtained with pathogenic strains of E.coli, such asE.coli 0157-H-7.

The sterilizer 100 includes a base or support member 106 with anadjustable column 194 that supports a hood member 102. In one form ofthe invention, shown in FIG. 9, the hood member 102 has four emitterpoints 112 mounted behind the grid 110. A series of circuit boards, suchas shown in FIG. 1, can be used to drive each respective emitter point.The power supply can use a conventional A.C. 110 volt source with anAC/DC converter in the base member 106 to provide a 9 volt D.C. sourcefor the circuit boards. Additionally, since the ozone would not begenerated adjacent an inhalation area of the user, the voltage can begreater than about 8 kV.

An alternative embodiment of a hand held sterilizer 114 is shown in FIG.10. The hood or housing portion 120 can be similar to the hood member102 of the embodiment of FIG. 9. An extended handle 116 can support a 9volt D.C. source, such as a 9 volt battery or six 1.5 volt AA batteriesin series. An off/on push button trigger or switch 118 can activate acorona discharge and the user can pass the hood portion 120 directlyover the surface or food to be sterilized. Preferably, the hood portionwill be positioned very close, e.g., 1 inch to 1/4 inch to the surface.

It is believed that the pathogens that can be acted upon by thesterilizer will not develop a resistance strain of pathogens as so oftenhappens in drugs and other forms of bacteria controls.

Those skilled in the art will appreciate that various adaptations andmodifications of the just-described preferred embodiment can beconfigured without departing from the scope and spirit of the invention.Therefore, it is to be understood that, within the scope of the appendedclaims, the invention may be practiced other than as specificallydescribed herein.

What is claimed is:
 1. A wearable personal corona discharge air purifiercomprising:a low voltage electric power source; a metallic memberelectrically connected to a first terminal of the electric power source;a high voltage supply connectable to the electric power source forproducing a corona discharge, the high voltage supply comprising:atransformer; with a primary and secondary winding; a transistoroscillator controlling current flow through the transformer so that thetransformer outputs an alternating current with a peak to valleypotential difference greater than a potential difference across theelectric power source; and a high voltage multiplier connected to thesecondary winding to convert the alternating current into pulsatingdirect current, relative to the electric power source, at an output ofthe voltage multiplier; and an emitter point connected to the output ofthe voltage multiplier and spaced apart from the metallic member, acorona discharge created around the emitter point ionizing air to formions which ions are accelerated towards the metallic member by apotential difference between the metallic member and the emitter point.2. The air purifier of claim 1, wherein the high voltage multipliercomprises a negative voltage multiplier producing a high negativevoltage.
 3. The air purifier of claim 1, wherein the high voltagemultiplier comprises multiple stages, each stage comprising a highvoltage diode and a capacitor.
 4. The air purifier of claim 1, whereinthe peak to valley potential difference of the alternating currentoutput by the transformer is 200 to 400 times greater than the potentialdifference across the electric power source.
 5. The air purifier ofclaim 1, wherein the alternating current output by the transformer is aseries of voltage spikes rather than a sinusoidally varying voltage. 6.The air purifier of claim 5, wherein the series of voltage spikes has afrequency of about 200 Hz.
 7. A wearable personal corona discharge airpurifier comprising:a battery; a metallic member electrically connectedto a positive terminal of the battery; a high voltage supply connectablebetween the terminals of the battery for producing a corona discharge,the high voltage supply comprising:a transformer having a primary and asecondary coil; a transistor with a tuning circuit controlling currentflow through the primary coil of the transformer, said transistor havinga gate connected to a tap of the transformer to form an oscillatorfeeding an alternating current into the primary coil of the transformerso that the secondary coil of the transformer outputs an alternatingcurrent of voltage spikes having voltage maxima of alternatingpolarities, said tuning circuit setting a frequency of the voltagespikes; and a high voltage multiplier connected to the secondary coil toconvert the alternating voltage spikes into a pulsating direct current,at an output of the multiplier; and an emitter point connected to anoutput of the voltage multiplier, for creating a corona discharge aroundthe emitter point, forming ozone, nitric oxide, and negative air ions,which ions are accelerated towards the metallic member by a potentialdifference between the grid and the emitter point causing a mass flow ofair through the metallic member.
 8. The air purifier of claim 7, whereinthe high voltage multiplier comprises multiple stages, each stage of themultiplier comprising a high voltage diode and a capacitor.
 9. The airpurifier of claim 7, wherein the series of voltage spikes has afrequency of about 200 Hz.
 10. A wearable personal corona discharge airpurifier comprising:an electric power source; a metallic memberelectrically connected to the electric power source; a high voltagesupply connectable to the electric power source for producing a voltage,the high voltage supply comprising:a step-up power inverter forproviding an alternating current with a greater peak to valley potentialdifference than a potential difference across the electric power source;and a high voltage cascade multiplier connected to an output of theinverter to convert the alternating current into pulsating directcurrent, at an output of the cascade voltage multiplier; and a needleemitter point connected to the output of the voltage multiplier andspaced apart from the metallic member, for creating a corona discharge,ions formed by the corona discharge being accelerated towards themetallic member by a potential difference between the metallic memberand the emitter point.
 11. The air purifier of claim 10, wherein thehigh voltage cascade multiplier comprises multiple stages, each stagecomprising a high voltage diode and a capacitor arranged as a cascadeseries voltage multiplier.
 12. The air purifier of claim 10, wherein thealternating current produced by the voltage inverter is a series of highvoltage spikes as opposed to a sinusoidally varying voltage.
 13. The airpurifier of claim 12, wherein the high voltage spikes output by theinverter each have a potential of about 2 kV.
 14. The air purifier ofclaim 13, wherein the series of voltage spikes has a frequency of about200 Hz.
 15. The air purifier of claim 14, wherein each voltage spikecomprises a voltage burst of about 50 μsec duration.
 16. A sterilizingcorona discharge air and surface purifier comprising:an electric powersource; a metallic member operatively connected to the electric powersource; a high voltage supply connectable to the electric power sourcefor producing a corona discharge, the high voltage supply comprising:atransformer; with a primary and secondary winding; a transistoroscillator controlling current flow through the transformer so that thetransformer outputs an alternating current with a peak to valleypotential difference greater than a potential difference across theelectric power source; and a high voltage multiplier connected to thesecondary winding to convert the alternating current into pulsatingdirect current, relative to the electric power source, at an output ofthe voltage multiplier; and at least one emitter point connected to theoutput of the voltage multiplier and spaced apart from the metallicmember, a corona discharge created around the emitter point ionizing airto form ions which ions are accelerated towards the metallic member by apotential difference between the metallic member and the emitter point,whereby a gas discharge is directed from the metallic member toencourage a microbial neutralization of a surface.
 17. The sterilizer ofclaim 16, wherein the high voltage multiplier comprises a negativevoltage multiplier producing a high negative voltage and comprisesmultiple stages, each stage comprising a high voltage diode and acapacitor.
 18. The sterilizer of claim 16, wherein a plurality ofemitter points are provided adjacent the metallic member.
 19. A handheld sterilizing corona discharge air and surface purifier comprising:ahousing; a metallic member positioned on the housing; at least oneemitter point positioned adjacent the metallic member; a power circuitconnected to the emitter point for providing a corona discharge toionize air to form ions, which ions are accelerated towards the metallicmember by a potential difference between the metallic member and theemitter point, whereby a gas discharge is directed from the metallicmember to encourage a microbial neutralization; and an outwardlyextending handle connected to the housing to enable a user to sweep thehousing across a surface to be sterilized, wherein the handle includes aD.C. battery source of power and an off/on switch for connecting thepower circuit to the source of power.
 20. A wearable personal coronadischarge air purifier comprising:a housing: an opening in the housingfor emitting purified air; a member electrically connected to a terminalof a power source, said member positioned proximate the opening: a highvoltage supply in the housing and connected between the terminals of thepower source for producing a corona discharge, the high voltage supplycomprising:a transformer having a primary and a secondary coil; atransistor with a tuning circuit controlling current flow through theprimary coil of the transformer, said transistor having a gate connectedto a tap of the transformer to form an oscillator feeding an alternatingcurrent into the primary coil of the transformer so that the secondarycoil of the transformer outputs an alternating current of voltage spikeshaving voltage maxima of alternating polarities; and a high voltagemultiplier connected to the secondary coil to convert the alternatingvoltage spikes into a pulsating direct current, at an output of themultiplier; and an emitter point adjacent the opening and connected toan output of the voltage multiplier thereby creating a corona dischargeof ions around the emitter point, which ions are accelerated towards themember by a potential difference between the member and the emitter,causing a mass flow of air from the housing.
 21. The air purifier ofclaim 20 wherein a distance between the emitter point and the member is1/4 to 1/2 inches.
 22. The air purifier of claim 20 wherein the memberis a metallic grid.
 23. The air purifier of claim 22 wherein saidmetallic grid is nickel plated.
 24. The air purifier of claim 22 whereinsaid metallic grid is coated with a catalyst for converting ozone intooxygen.